1. Field of the Invention
The invention relates to position sensors and more specifically to an apparatus for detecting the position coordinates and orientation of a targeting device.
2. Description of the Related Art
Conventional optical coordinate detection in most video game systems makes use of the vertical and horizontal synchronizing signals in the video signal generated by a game device. In order to define the location of an object on a video screen, the game device is provided with a horizontal counter for counting the columns on a display screen, a vertical counter for counting the number of scanning lines, and a real, user manipulated device, such as a model gun, sword, paint brush, boxing glove, shield, etc. for interacting with images on the display screen. The device is provided with a photosensor which receives light from the scanning lines shown on the display screen, and which has a certain degree of directionality. In other words, the device does not emit a light ray, but rather it actually receives a portion of the light emitted from the display.
Presently known shooting game machines may include an object such as a gun, and function such that the display screen turns white for one frame when the game controller detects that the player has pulled a trigger on the model gun. Starting at the next vertical blanking period following the xe2x80x9cshotxe2x80x9d, white pixels are displayed and counted starting from the upper left along a scan line. As each scan line is filled and counted, the system looks for where the shot from the gun would have impacted the screen by continuously looking for an illumination detection by a photosensor in the gun, and thus the targeted position is detected based on the pixel and scan line count at which the photosensor receives light from the raster scanning screen.
Unfortunately, the display screen turns white every time the trigger of the model gun is pulled. This may be used as a benefit in simulating a gun flash and giving the player instant feedback, but the intensity of the light from the white screen can be also annoying to the player. Further, when using a rapid-fire gun, the display screen is constantly flickering and reduces the quality of the display screen image. Also, this places an extra stress on the power supply of the monitor. Putting up a screen of white is a big jolt to the power supply and has been known to cause power supply failure.
Additionally, because NTSC is displayed at 59.9 Hz (60 Hz.), the fastest one can update the pointer value is 60 Hz/2. This allows for one screen frame of video to be interlaced between one white position finding frame. Actual games include more frames of video between successive white frames, since the image quality is unsatisfactory with so many white screens. However, there are many times when it would be desirable to have a faster update, such as when tracking rapid movements or simulating rapid gun-fire, such as with a machine gun.
Furthermore, with the advent of digital displays, the conventional method does not work in a straightforward manner because digital displays do not normally display the scanning lines. Additionally, the conventional method only determines the location on the display screen to which the model gun is pointing. The position coordinates of the model gun and the vector in which the model gun is pointed are not determined. Accordingly, input into the shooting game cannot generate scenes from the user""s perspective and generate simulated bullet traces because the position of the gun is not known. Also, known shooting games cannot take advantage of the increased computer processing speeds and more realistic digital displays. In view of the above, it would be a significant improvement in the technology to provide a targeting system that does not depend on a raster scanning display screen and also one that can detect and input the position of the targeting device and the direction it is pointing into the video game system.
In accordance with the invention, there is disclosed an apparatus and a method for determining a targeting device""s position coordinates and orientation in such a way as to be unrelated to the video being displayed.
In one embodiment, a position sensing apparatus includes a targeting device, a plurality of transmitters for transmitting light signals, a plurality of receivers capable of detecting the light signals from the transmitters, and a receiver circuit connected to the receivers. The receiver circuit develops distance signals representative of the distance of the transmitters from the receivers and sends the signals to a processor to determine the three-dimensional coordinate position and orientation of the targeting device with respect to a display monitor.
Another embodiment is a targeting game machine including a display monitor for displaying a target and at least one targeting device. The game machine includes at least three transmitters for emitting infrared light signals, wherein at least three transmitters are mounted on the at least one targeting device, and at least three photodiode receivers capable of detecting the light signals from said transmitters, wherein the receivers are mounted about the display monitor. The game machine also includes a receiver circuit electrically connected to said receivers, wherein the receiver circuit generates signals in relation to the intensity of the infrared light signals detected by the receivers, the generated signals representing the distance of the transmitters from the receivers, and a processor for processing the signals to determine the three-dimensional coordinate position and orientation of the targeting device with respect to the display monitor.
Another embodiment is a method of detecting a targeted position of a targeting device relative to a display monitor for use in a targeting game machine. The targeting device and the display monitor have a plurality of transmitters and a plurality of receivers fixedly mounted thereto. The method includes emitting light signals from the transmitters, detecting light signals emitted from the transmitters at the receivers, and calculating the three-dimensional position and orientation of the targeting device.